1. Field of the Invention
The present invention relates to wound closure devices for use during and after invasive medical procedures, and more particularly to, electrosurgical devices that include a stapler for closing a wound and an integrated mechanism which applies electrical energy to the body tissue within which the wound is formed to cauterize the wound site.
2. Background of the Related Art
The application of electrical energy to a surgical site for the purpose of cutting or cauterizing body tissue has been known for some time in the medical community and is generally referred to as either electrocautery and electrosurgery. Often “electrocautery” is used to describe “electrosurgery,” but this is incorrect.
Electrocautery refers to applications wherein the electrical energy is supplied in a direct current, i.e., electrons flowing in one direction. In contrast, in electrosurgery an alternating current energy supply is used. Moreover, during electrocautery, current does not enter the patient's body, but flows though a wire or needle associated with the instrument and due to their impedance the wire/needle become very hot. The surgeon places the hot wire or needle in contact with body tissue so as to cut or cauterize the tissue.
In electrosurgery, the patient's body is included in the circuit. The circuit is composed of the generator, active electrode, patient, and patient return electrode. Pathways to ground are numerous but may include the operating room table, stirrups, staff members and equipment. Electrosurgery involves the cutting and/or coagulating of body tissue by application of high frequency electrical current.
In bipolar electrosurgery, the electrical current is applied through an electrode which contacts the body tissue to be treated. A return electrode is placed in contact with or in close proximity to the current-supplying electrode such that an electrical circuit is formed between the two electrodes. In this manner, the applied electrical current is limited to the body tissue positioned between the electrodes. The patient's tissue provides the impedance, producing heat as the electrons overcome the impedance. When the electrodes are sufficiently separated from one another, the electrical circuit is open and thus inadvertent contact of body tissue with either of the separated electrodes does not cause current to flow.
U.S. Pat. No. 5,573,534 to Stone, which is herein incorporated by reference in its entirety, discloses a bipolar surgical instrument for selectively grasping, manipulating, cutting and/or coagulating body tissue. To perform tissue cutting and/or coagulation, a high frequency power supply is connected to the bipolar instrument. Each electrode of the bipolar instrument is electrically isolated within the instrument and is separately connected to the high frequency power supply. Typical power supplies such as those available from Valleylab, Inc. of Boulder, Colo., are R.F. (i.e., radio frequency) generators which can produce different electrical waveforms to effect various electrosurgical procedures.
A waveform of continuous sinewaves alternating from positive to negative at the operating frequency of the R.F. generator is employed to cut tissue. Such a waveform creates short, intense electrical sparks to rapidly heat tissue; cells are exploded and the heat dissipated as steam. In contrast, a waveform consisting of pulsating sine waves alternating from positive to negative at the operating frequency of the R.F. generator is employed to coagulate tissue. Such a waveform creates longer, less intense sparks which heat tissue less rapidly, allowing heat to be dissipated more widely than during cutting. A combination of the cutting and coagulating waveforms produces the capability to cut tissue with enhanced hemostasis over the pure cutting waveform.
Due to its versatility and clinical effectiveness, monopolar is the most commonly used electrosurgical modality. In monopolar electrosurgery, the active electrode is in contact with the surgical site and the patient return electrode is somewhere else on the patient's body. The current passes through the patient as it completes the circuit from the active electrode to the patient return electrode.
U.S. Pat. Nos. 6,755,842 and 6,506,210, disclose advanced wound site management systems and methods. More specifically, these patents disclose a staple, stapler and introducer for closing a wound and for wound site management. The staple is deformable, and includes a plurality of tissue-piercing prongs which are expanded outwardly, inserted into tissue and collapsed inwardly to close the wound. The stapler includes a plurality of mechanisms to deform the staple into various positions. An introducer is provided that includes a plurality of spaced-apart wire guides for securing and centering the wound opening during a medical procedure, and during closure of the wound. The disclosures of U.S. Pat. Nos. 6,755,842 and 6,506,210 are herein incorporated by reference in their entirety.
A disadvantage of the wound site management systems disclosed in U.S. Pat. Nos. 6,755,842 and 6,506,210 and other prior art devices and systems is that they do not include an integrated cauterizing mechanism. As a result, a separate device must be used to cauterize the wound after the stapler and introducer have been removed. This not only adds complexity to the surgical procedure, but increases the time required for hemostasis.
In view of the above, there is a need for an improved wound closure device for use during and after invasive medical procedures which includes a stapler for closing the wound and an integrated mechanism for applying electrical energy to the body tissue in order to effect cauterization of the wound site.